In an assembly method of a magnetic fluid seal (100) that includes a magnetic field forming member (130) divided in a circumferential direction, a magnetic pole member (120) including a pair of magnetic fluid retaining portions (121, 122) and a coupling portion (123) that couples them, a first bearing (160) and a second bearing (170), a step of fixing the first bearing (160) to a shaft (400) in a state in which the shaft (400) is directed in a vertical direction, a step of attaching the magnetic pole member (120) from above the first bearing (160), a step of fixing the second bearing (170) to the shaft (400) from above the magnetic pole member (120) to thereby fix the magnetic pole member (120) in a state in which the magnetic pole member (120) is positioned with respect to the shaft (400); and a step of attaching the magnetic field forming member (130) between the pair of magnetic fluid retaining portions (121, 122) are performed in order.

A reverse rotation prevention device and a magnetic fluid seal mechanism disposed in front of the reverse rotation prevention device are provided. The reverse rotation prevention device comprises an inner ring, an outer ring disposed outside the inner ring, and a plurality of rollers disposed between the inner ring and the outer ring. The magnetic fluid seal mechanism comprises a cylindrical member that is a magnetic body, a ring-shaped magnet, a first magnetic plate and a second magnetic plate, and a magnetic fluid held by a magnetic force. A cylindrical intermediate member that is a non-magnetic body disposed between the inner ring and the cylindrical member is further provided.

One object is to provide a drone capable of achieving desired performance by preventing entry of foreign matter such as water droplets or dust particularly into a power portion thereof. A drone of the present invention is provided with a fixed section having a motor housing for housing a motor therein and a rotary section having a propeller shaft supported via a bearing so as to be rotatable with respect to the motor housing and configured to rotate integrally with the propeller. In an opposed portion where fixed-side components constituting the fixed section and rotary-side components constituting the rotary section are opposed to each other, there is provided a foreign matter entry prevention unit configured to prevent foreign matter from entering an inside of the motor housing.

Provided is a magnetic fluid sealed bearing unit that provides excellent handling ease and workability in incorporating the bearing unit into a rotary shaft portion and exhibits a stable sealing capability. A magnetic fluid sealed bearing unit of the present invention has an inner ring and an outer ring, each made of a magnetic material, a plurality of rolling members interposed between the inner ring and the outer ring, a magnetic seal mechanism arranged between the inner ring and the outer ring and configured to inhibit entry of foreign substances toward the plurality of rolling members, a non-magnetic inner ring-side support member fitted and retained on the inner ring, and a non-magnetic outer ring-side support member fitted and retained on the outer ring.

An object of the present invention is to provide a fishing reel wherein a bearing rotatably supporting a drive shaft securely shuts out water from its interior so as to maintain stable sealing and thus smooth rotation for a long period wherein such a bearing can be readily built in. In accordance with one aspect, the fishing reel of the present invention includes a drive shaft to be rotationally driven for winding a fishing line around a spool. The drive shaft is rotationally supported by a magnetic fluid sealed bearing having an inner ring magnetic fluid retained between an inner ring and a polar plate retaining a magnet and/or between the inner ring and the magnet, and an outer ring magnetic fluid retained between an outer ring and the polar plate retaining the magnet and/or between the outer ring and the magnet.

The present invention provides a magnetic fluid sealed bearing having a stable sealing performance and allowing easy build-in of a magnetic sealing mechanism into the bearing. A magnetic fluid sealed bearing according to the present invention includes: an inner ring and an outer ring; a plurality of rolling members disposed between the inner ring and the outer ring; a ring-shaped polar plate mounted on an inner circumferential surface of the outer ring such that a gap is produced between the ring-shaped polar plate and an outer circumferential surface of the inner ring; a ring-shaped magnet attached to an axially inner side surface of the ring-shaped polar plate, the ring-shaped magnet forming magnetic circuits on both the outer ring side and the inner ring side; and an inner ring magnetic fluid retained in the magnetic circuit on the inner ring side for sealing the gap.

The present invention is a line roller unit that includes a line roller, a bearing, a cylindrical member, and a first magnetic seal. The line roller possesses a guider on its periphery surface that guides a fishing line. The bearing is set up on the inner circumference of the line roller, with the cylindrical member possessing a holding part that holds bearing. The cylindrical member is set up on the inner circumference of bearing. The first magnetic seal possesses both a first magnet and a first holding member that holds the first magnet, and the first magnetic seal forms the first magnetic circuit for holding the magnetic liquid at the space between the cylindrical member. The first magnetic seal is set up on the line roller.

Provided is a bearing with a magnetic fluid seal reliably maintaining sealing of a rolling element section in the bearing and having a structure ensuring high productivity. In a bearing with a magnetic fluid seal according to the present invention, a plurality of rolling elements 7 are disposed between an inner ring and an outer ring, and a ring-shaped magnet is arranged at an opening side of the inner and outer rings so as to retain magnetic fluid, so that the plurality of rolling elements are sealed. The magnet is magnetized so that magnetic poles are oriented in an axial direction. A ring-shaped pole plate is arranged to be in contact with an outer side surface of the magnet in the axial direction. Outer-ring-side magnetic fluid is retained between the outer ring and the magnet, and inner-ring-side magnetic fluid is retained between the inner ring and the pole plate.

In a bearing according to an embodiment, a pair of magnets is arranged such that sides of the magnets opposed to each other with rolling members interposed therebetween have different magnetic polarities from each other. A magnetic fluid sealed bearing according to another embodiment includes a non-magnetic spacer disposed between a magnet of one of magnetic fluid seals and a magnet of the other of the magnetic fluid seals so as to form a magnetic circuit that penetrates outer and inner rings and goes around the rolling members.

The present invention provides a magnetic fluid sealed bearing having a stable sealing performance and allowing easy build-in of a magnetic sealing mechanism into the bearing. A magnetic fluid sealed bearing according to the present invention includes: an inner ring and an outer ring; a plurality of rolling members disposed between the inner ring and the outer ring; a ring-shaped polar plate mounted on an inner circumferential surface of the outer ring such that a gap is produced between the ring-shaped polar plate and an outer circumferential surface of the inner ring; a ring-shaped magnet attached to an axially inner side surface of the ring-shaped polar plate, the ring-shaped magnet forming magnetic circuits on both the outer ring side and the inner ring side; and an inner ring magnetic fluid retained in the magnetic circuit on the inner ring side for sealing the gap.